Agricultural combines are self-propelled vehicles that harvest crop materials growing in a field. Internal mechanisms inside combines receive crop plants severed from the ground, thresh them, separate grain from the remainder of the crop plants, and clean the resulting grain.
The threshing and separating mechanisms produce a stream of residue generally called “straw”. The cleaning mechanisms produce a secondary stream of residue generally called “chaff”.
These two residue streams are typically handled differently inside the combine. The straw can be chopped or not chopped. The straw and/or chaff can be spread widely over the ground, or it can be deposited in a continuous narrow pile immediately behind the combine, generally called a “windrow”.
In order to provide this different processing and distribution of residue, various channels or conduits for material flow are provided within the combine itself that can be opened and closed, connected and disconnected by repositioning elements within the combine itself.
In one arrangement, shown in US 2016/0135377 A1, a combine has a straw chopper disposed in an upper rear portion of the combine that rotates in a generally clockwise direction (FIGS. 3-4).
When door 78 is closed, it provides a barrier that extends over the top of the straw chopper and closes off a windrowing channel. This barrier deflects straw (and air from a cleaning fan) over the top of the chopper, downwardly and behind the chopper rotor. The straw is then chopped behind the chopper rotor between a knife and blades extending from the chopper rotor. The chopped straw falls downward behind the chopper rotor and is distributed over the ground.
When door 78 is open, this barrier is removed, and straw and air can flow over the top of the chopper rotor. Straw and air flowing over the top of the chopper rotor flows into a windrowing conduit. Passing through the windrowing conduit, the un-chopped straw is deposited on the ground behind the combine as a windrow.
One problem with this arrangement is that it blocks the free flow of air out of the combine when straw is being chopped. The door 78 blocks the windrowing conduit and prevents air from flowing freely out of the combine when the combine is configured to chop straw. Air (provided by the cleaning fan 52) is the medium that carries the residue through and out the rear of the combine. When it is blocked, it increases the internal pressure inside the combine, reduces the airflow rate, and the operation of the combine is limited.
It would be beneficial to provide greater airflow through the combine than is provided in the prior art.
It is an object of this invention to provide greater airflow.